A method for controlling fuel pressure in an internal combustion engine consuming a gaseous fuel and a liquid fuel comprises steps of determining a gaseous fuel pressure target value as a function of an engine operating condition, pressurizing the liquid fuel to a liquid fuel pressure based on the gaseous fuel pressure target value, and regulating gaseous fuel pressure from the liquid fuel pressure. The gaseous fuel pressure equals the gaseous fuel pressure target value to within a predetermined range of tolerance. A corresponding system controls fuel pressure in a gaseous fuelled internal combustion engine.
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1. A fuel system for an injection valve that introduces a liquid fuel and a gaseous fuel separately and independently of each other into a combustion chamber of an internal combustion engine, the fuel system comprising: a liquid fuel supply; a gaseous fuel supply; a liquid fuel pumping apparatus in fluid communication with the liquid fuel supply and supplying the liquid fuel to the injection valve at a pressure suitable for injecting the liquid fuel into the combustion chamber; a pressure regulator in fluid communication with the gaseous fuel supply and supplying the gaseous fuel to the injection valve at a pressure suitable for injecting the gaseous fuel into the combustion chamber, the pressure regulator being unresponsive to liquid fuel pressure downstream from the liquid fuel pumping apparatus; a first pressure sensor for measuring liquid fuel pressure downstream from the liquid fuel pumping apparatus; a second pressure sensor for measuring gaseous fuel pressure downstream from the pressure regulator; and a controller operatively connected with the liquid fuel pumping apparatus, the pressure regulator, the first pressure sensor and the second pressure sensor, and programmed to: monitor pressure signals from the first pressure sensor and the second pressure sensor that are representative of liquid fuel pressure and gaseous fuel pressure respectively; and command the liquid fuel pumping apparatus and the pressure regulator such that a target pressure differential between the liquid fuel pressure and the gaseous fuel pressure is maintained within a predetermined range of tolerance.
A fuel injection system for a dual-fuel (liquid and gaseous) internal combustion engine has separate injection valves for each fuel type. It includes a liquid fuel supply, a gaseous fuel supply, a liquid fuel pump to pressurize the liquid fuel, and a pressure regulator for the gaseous fuel. Crucially, the gaseous fuel pressure regulator operates independently of the liquid fuel pressure. Liquid and gaseous fuel pressure sensors provide feedback to a controller. The controller adjusts the liquid fuel pump and gaseous fuel pressure regulator to maintain a target pressure difference between the liquid and gaseous fuels within a defined tolerance range.
2. The fuel system of claim 1 , wherein the pressure regulator is a variable pressure regulator that can adjustably regulate the gaseous fuel pressure.
The fuel injection system described previously, which manages both liquid and gaseous fuels, uses a *variable* pressure regulator for the gaseous fuel. This regulator can be actively adjusted by the controller to change the gaseous fuel pressure, enabling dynamic control of the target pressure differential between liquid and gaseous fuels based on engine demands. This adjustability is a key feature differentiating this system.
3. The fuel system of claim 1 , wherein the target pressure differential is a function of engine operating conditions.
In the dual-fuel injection system maintaining a target pressure differential between liquid and gaseous fuel, the specific target pressure differential is not fixed. Instead, it's dynamically adjusted as a function of engine operating conditions. The engine's controller continuously modifies the target pressure difference based on parameters like engine speed, load, and temperature, to optimize combustion across various scenarios.
4. The fuel system of claim 3 , wherein the target pressure differential increases as engine load increases.
For the dual-fuel injection system, where the target pressure differential is based on engine operating conditions, specifically, the system increases the target pressure differential between the liquid and gaseous fuels as the engine load increases. Under higher loads, the difference in pressure between the two fuels is actively widened by the controller to ensure proper fuel delivery and combustion.
5. The fuel system of claim 3 , wherein the target pressure differential is reduced at lower load engine operating conditions compared to higher load engine operating conditions.
For the dual-fuel injection system, where the target pressure differential depends on operating conditions, the system *reduces* the target pressure differential between the liquid and gaseous fuels at lower engine loads compared to higher engine loads. By decreasing the pressure difference at light loads, the system improves fuel efficiency and reduces emissions during those operating conditions.
6. The fuel system of claim 5 , wherein the target pressure differential is reduced at idle compared to higher load engine operating conditions.
Continuing from the dual-fuel system's strategy of adjusting the target pressure differential according to engine load, at idle, the target pressure differential between the liquid and gaseous fuels is reduced even further compared to higher engine load conditions. This minimizes fuel consumption and optimizes combustion stability when the engine is idling.
7. The fuel system of claim 1 , wherein the target pressure differential is maintained during transient engine operating conditions.
In the described dual-fuel injection system, maintaining a target pressure differential between liquid and gaseous fuel, the system actively maintains the specified target pressure differential even during *transient* engine operating conditions (e.g., rapid accelerations or decelerations). The controller responds quickly to changing engine demands to keep the pressure difference within the desired range, ensuring stable and efficient combustion during dynamic situations.
8. A method for controlling liquid fuel pressure and gaseous fuel pressure for an injection valve that introduces a liquid fuel and a gaseous fuel separately and independently of each other into a combustion chamber of an internal combustion engine, the method comprising: monitoring the liquid fuel pressure; monitoring the gaseous fuel pressure; commanding a pump to pressurize the liquid fuel; and commanding a regulator to regulate the gaseous fuel; wherein the regulator is unresponsive to the liquid fuel pressure downstream from the pump and a target pressure differential in response to the monitoring is maintained between the liquid fuel pressure and the gaseous fuel pressure within a predetermined range of tolerance.
A method for controlling liquid and gaseous fuel pressures in a dual-fuel internal combustion engine involves independently injecting both fuels into the combustion chamber. The method includes monitoring the liquid fuel pressure and the gaseous fuel pressure, commanding a pump to pressurize the liquid fuel, and commanding a regulator to regulate the gaseous fuel. The gaseous fuel regulator does *not* respond to changes in liquid fuel pressure downstream of the pump. The method maintains a target pressure difference between the two fuels within a defined tolerance range based on the monitored pressures.
9. The method of claim 8 , wherein the target pressure differential is a function of engine operating conditions.
In the method for controlling liquid and gaseous fuel pressures in a dual-fuel engine, the target pressure differential between the liquid and gaseous fuels is not static. It is dynamically adjusted as a function of the current engine operating conditions. The control system continuously updates the target pressure difference based on parameters like engine speed, load, and temperature.
10. The method of claim 9 , further comprising reducing the target pressure differential at lower load engine operating conditions compared to higher load engine operating conditions.
Expanding on the method where the target pressure differential depends on engine conditions, the method further includes reducing the target pressure differential at lower engine load conditions compared to higher engine load conditions. Decreasing the pressure difference at light loads optimizes fuel efficiency and reduces emissions during those operating states.
11. The method of claim 10 , further comprising reducing the target pressure differential at idle compared to higher load engine operating conditions.
In the method for controlling fuel pressures by adjusting the target pressure differential based on engine load, the method includes reducing the target pressure differential at idle *even further* compared to the levels used at higher load engine operating conditions. This minimizes fuel consumption and stabilizes combustion when the engine is idling.
12. The method of claim 9 , further comprising increasing the target pressure differential as engine load increases.
In the method that adjusts the target pressure differential according to engine conditions, the method specifically increases the target pressure differential between the liquid and gaseous fuels as the engine load increases. This action of increasing the pressure difference at higher loads ensures proper fuel delivery and combustion under heavier demands.
13. The method of claim 8 , further comprising maintaining the target pressure differential during transient engine operating conditions.
In the method for controlling liquid and gaseous fuel pressures, the method includes maintaining the specified target pressure differential even during transient engine operating conditions (e.g., rapid accelerations or decelerations). The controller actively works to keep the pressure difference within the defined tolerance range, even as engine demands rapidly change, ensuring stable and efficient combustion during dynamic situations.
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October 1, 2014
April 18, 2017
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